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Massive Study Using Apple Watch Spots Heart Issues, With Limits

Robert Langreth, Bloomberg News

Apple Watch Series 4 Photographer: Anthony Kwan/Bloomberg
, Bloomberg

(Bloomberg) -- Researchers from Stanford University’s School of Medicine presented results from a giant study sponsored by Apple Inc. that showed the Apple Watch can sometimes spot patients with undiagnosed heart-rhythm problems, without producing large numbers of false alarms.

The Apple-sponsored trial enrolled 419,297 people and was one of the largest heart-screening studies ever. The study, details of which are being presented today at the American College of Cardiology conference in New Orleans, used the watch’s sensors to detect possible atrial fibrillation.

“The findings are exciting and encouraging, but clearly there is a lot more to be done,” said Lloyd Minor, dean of Stanford’s medical school. The study could help pave the way for more research into how modern digital tools can help improve health.

People who have atrial fibrillation are at risk of blood clots and strokes. In the U.S., it causes 750,000 hospitalizations a year and contributes to 130,000 deaths, according to the Centers for Disease Control and Prevention. Because it doesn’t always produce outward symptoms, it can go undiagnosed.

According to results presented Saturday, about 0.5 percent of patients in the study -- or almost 2,100 people -- received notices from their watch indicating that they might have a heart-rhythm problem. That relatively low number showed that the technology wasn’t inundating people with worrisome alerts.

Further Study

Of the minority of patients who got notifications and agreed to wear a portable electrocardiogram for up to a week, about 34 percent were found to have atrial fibrillation. That may be because atrial fibrillation can come and go, and doesn’t necessarily mean that the other 66 percent didn’t have the condition, Mintu Turakhia, a Stanford professor of cardiovascular medicine and one of the leaders of the study, said in a statement.

One unusual feature of the study is that it allowed people to participate without ever visiting a doctor in person. When the watch detected repeated periods of irregular heart beats, patients got alerts to call in for a virtual consultation.

The study isn’t likely to immediately shift medical practice.

“We have got more work to do to understand specifically how the data form this technology can be integrated into routine clinical assessment and patient management decisions,” said Kenneth Mahaffey, a cardiologist at the Stanford University School of Medicine, who chaired the study.

To contact the reporter on this story: Robert Langreth in New York at rlangreth@bloomberg.net

To contact the editors responsible for this story: Drew Armstrong at darmstrong17@bloomberg.net, James Ludden